Seroprevalence and risk factors of Brucella infection in commercial cattle farms in the Lake Zone of Tanzania

Brucellosis is an important zoonotic disease among livestock and humans worldwide and in Low-and-Middle Countries (LMICs) including Tanzania. The aim of this study was to determine the factors that could influence seroprevalence of brucellosis in commercial cattle farms. A cross-sectional study was conducted in a total of 54 commercial cattle farms randomly selected in Kagera, Mara, and Mwanza regions of the Lake Zone in Tanzania. Serum samples were collected from 1,080 cattle comprising both dairy and beef animals of both sexes and tested for Brucella-specific antibodies using Rose Bengal Plate Test (RBPT). Positive samples were confirmed by using competitive Enzyme-linked Immunosorbent Assay (c-ELISA). Animals in each farm were randomly selected for blood collection whereby a total number of 20 adult animals from both sexes were involved in the study. Descriptive statistics and multivariable regression analysis were conducted to assess the risk factors associated with brucellosis.The overall seroprevalence of brucellosis was 6.9% at the animal level and 51.9% at the farm level. Medium scale farms Odds ratio (OR = 11.304; Confidence Interval 95% CI 1.140 – 112.108;) and small - scale farms (OR = 37.170; 95% CI 1.119 – 1235.006) demonstrated a significantly higher likelihood of seropositivity to brucellosis than large - scale farms. Dairy cattle farms were less likely to be seropositive (OR = 0.046; 95% CI 0.003 – 0.728;) than beef cattle farms. The findings from the present study indicated that more than half of the farms are positive for Brucella antibodies. The study also revealed that the scale of production and functional type of cattle increase the risk of seropositivity. The findings provide baseline information for the development of targeted intervention programme in the control of brucellosis.